Mist

She's a member of the Übermensch Union. The World of "Mist" is the ability of Mist. This allows Mist to create illusory worlds from water vapor. For the ability to take effect, the mist must shroud a certain area that it wishes to place the illusion on. Inside the mist, she can freely change the physical "world" inside it. (Source: Area D - Inou Ryouiki Wiki)